Add a feature layer from a portal item

Before starting this tutorial, you need the following:

1. An ArcGIS Location Platform or ArcGIS Online account.

2. A development and deployment environment that meets the system requirements.

3. An IDE for Android development in Kotlin.

Option 1: Develop the code

Open an Android Studio project with Gradle

1. Open the project you created by completing the Display a map tutorial.

2. Continue with the following instructions to use an ArcGIS portal item to access and display a feature layer in a map.

3. Modify the old project for use in this new tutorial.

   Expand for detailed instructions

   1. On your file system, delete the .idea folder, if present, at the top level of your project.

   2. In the Android view, open app > res > values > strings.xml.

      In the <string name="app_name"> element, change the text content to Add a feature layer from a portal item.

      strings.xml

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      <resources>
          <string name="app_name">Add a feature layer from a portal item</string>
      </resources>

   3. In the Android view, open Gradle Scripts > settings.gradle.kts.

      Change the value of rootProject.name to "Add a feature layer from a portal item".

      settings.gradle.kts

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      dependencyResolutionManagement {
          repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
          repositories {
              google()
              mavenCentral()
              maven { url = uri("https://esri.jfrog.io/artifactory/arcgis") }
          }
      }
      
      rootProject.name = "Add a feature layer from a portal item"
      include(":app")

   4. Click File > Sync Project with Gradle files. Android Studio will recognize your changes and create a new .idea folder.

Add import statements

In the Android view, open app > kotlin+java > com.example.app > MainScreen.kt. Replace the import statements with the imports needed for this tutorial.

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@file:OptIn(ExperimentalMaterial3Api::class)

package com.example.app.screens

import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.res.stringResource
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.PortalItem
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.portal.Portal
import com.arcgismaps.toolkit.geoviewcompose.MapView
import com.example.app.R

Add a feature layer to the map

You can reference an item (such as a web map or feature layer) hosted in a portal (such as ArcGIS Online) using its unique item ID. You will reference the Trailheads Styled feature layer stored in ArcGIS Online using its item ID: 2e4b3df6ba4b44969a3bc9827de746b3. You will then add that feature layer to your map's collection of data layers (operational layers).

1. In MainScreen, before the code that creates the ArcGISMap, create a new Portal referencing ArcGIS Online as the url parameter and Portal.Connection.Anonymous for the connection parameter.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
       }
   
   }

2. Then, create a PortalItem instance, passing portal and the id of the portal item that the feature layer will use.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       val portalItem = PortalItem(
           portal = portal,
           itemId = "2e4b3df6ba4b44969a3bc9827de746b3"
       )
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
       }
   
   }

3. Next, create a FeatureLayer using FeatureLayer.createWithItem(), to which you pass the portal item.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       val portalItem = PortalItem(
           portal = portal,
           itemId = "2e4b3df6ba4b44969a3bc9827de746b3"
       )
   
       val featureLayer = FeatureLayer.createWithItem(portalItem)
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
       }
   
   }

4. In the apply block for ArcGISMap, add the feature layer to the map.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       val portalItem = PortalItem(
           portal = portal,
           itemId = "2e4b3df6ba4b44969a3bc9827de746b3"
       )
   
       val featureLayer = FeatureLayer.createWithItem(portalItem)
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
           operationalLayers.add(featureLayer)
   
       }
   
   }

5. Click Run > Run > app to run the app.

You should see a map of trail heads in the Santa Monica mountains. Double tap, Drag, pinch in, and pinch out on the map view to explore the map.

Option 2: Download the solution

1. Click the Download solution link in the right-hand side of this page.

2. Unzip the file to a location on your machine.

3. Run Android Studio.

4. Go to File > Open.... Navigate to the solution folder and click Open.

   On Windows: If you are in the Welcome to Android Studio dialog, click Open and navigate to the solution folder. Then click Open.

Since the downloaded solution does not contain authentication credentials, you must first set up authentication to create credentials, and then add the developer credentials to the solution.

Set up authentication

To access the secure ArcGIS location services used in this tutorial, you must implement API key authentication or user authentication using an ArcGIS Location Platform or an ArcGIS Online account.

Set developer credentials in the solution

To allow your app users to access ArcGIS location services, use the developer credentials that you created in the Set up authentication step to authenticate requests for resources.

Run the app

Click Run > Run > app to run the app.

You should see a map of trail heads in the Santa Monica mountains. Double tap, Drag, pinch in, and pinch out on the map view to explore the map.